Influence of subcellular metal compartmentalization in different prey on the transfer of metals to a predatory gastropod

Marine snails Thais clavigera accumulate high metal concentrations in their bodies and trophic transfer may play an important role in metal bioaccumulation in this top predator in the intertidal rocky shore. In this study, we examined the relationship between the subcellular metal distribution in prey (barnacles, mussels, oysters, herbivorous snails, limpets) and the assimilation efficiency (AE) of cadmium, silver and zinc in T. clavigera. The metal subcellular distributions in the oyster prey were also modified and the metal AEs in T. clavigera measured. We further purified the subcellular fractions of different prey and determined how the biochemical properties of different fractions affected the metal AEs. Results showed that the AEs of each metal from different prey were comparable and generally high (50 to 90 %). Significant positive correlation was found between the Cd AEs and the metallothionein-like protein (MTLP) fraction, and between the AEs of Zn and the trophically available metal (TAM) fraction. For Ag, no relationship between its AE and any of the subcellular fractions was documented. When T. clavigera fed on oysters with different exposure regimes, the metal AEs were not significantly correlated with the metal subcellular partitioning in the oysters. Furthermore, the AEs of Ag, Cd and Zn were similar among the different biochemical fractions. For these 3 metals, T. clavigera assimilated 60 to 85 % from the insoluble fraction, 40 to 80 % from the heat-sensitive protein fraction, 45 to 90 % from the MTLP fraction, and 40 to 80 % from the metal-rich granule (MRG) fraction. Our results imply that metals bound to the insoluble fraction or MRG were also bioavailable to T. clavigera. This study may help to better understand the mechanisms of metal transfer along the intertidal food chain. © Inter-Research 2005.